Telling the OP to throw out a multi thousand dollar 24 port managed GigE
switch due to a minor issue with one PC or server is not very sage advice.

I said "try changing", not "throw out" (reading and quoting is a basic
skill). Having sold many _multi-thousand-Euro-switches_ let me tell you
that they can be broken right from the start. DOA should ring a bell. A
simple temporary change of the switch (often the replacement is provided
by the vendor) would immediately show if this could be the problem.
It's a bit of a general problem on lists like this one (very technical
ones) that some very smart people dislike simple straight forward
solutions to be checked first, although it happens all the time that
smart people stumble over simple problems. Instead they like to tell
other people they're not sage enough.
So sorry for my "Is the cable ok?" approach as a first aid, I will keep
my mouth shut now, knowing that there's a savvy elite around.

Stan definitely did not exercise sufficient reading comprehension.
Adding the word "temporarily" would have reduced all ambiguity, though.
--
"History does not long entrust the care of freedom to the weak
or the timid." Dwight Eisenhower